Autotransfusion systems can often be employed during a surgical procedure to recover and wash shed blood for re-infusion into the patient when donated blood is scarce or unavailable or when there is concern regarding the safety of the donated blood. The autotransfusion system may employ an aspiration system for recovering the shed blood. During the aspiration process, shed blood may be aspirated and directed through a gross clot pre-filter and into a collection vessel. Anticoagulant must be added to the collected blood to prevent clot formation within the collection vessel.
The mixture of collected blood and anticoagulant may be washed by the addition of a wash solution. The wash solution serves to dilute the blood. After dilution with the wash solution, the red cells may be separated from the diluted blood mixture by centrifugation or by gravity sedimentation. During centrifugation and/or gravity sedimentation, the red cells sediment and collect at the bottom of the vessel as packed red cells. The sedimentation of the red cells causes a substantial elutriation of various fluids and particles from packed red cells, including plasma, tissue fluids, anticoagulant, and washing solution. The packed red cells are suspended in residual supernatant. The packed red cell product may then be removed and transferred to a reinfusion bag for reinfusion into the patient from whom it was taken.
Although autotransfusion systems find wide application, their utility is mitigated by the slowness of the gravity sedimentation step and/or the complexity and labor involved with the centrifugation step. What is needed is an autotransfusion system which employs a simple but accelerated gravity sedimentation step for reducing the time delay between collection and reinfusion.